Stock single exhaust to dual, what size kit?

[Danno]

I have a 72 fastback, 302 2v,with a single exhaust. This is a stock system I want to change over to a dual exhaust. Shopping for kits and wondering what size, 2", 2 1/4", or 2 1/2"? This would be from the manifold, no headers. I had a '66 289 and used an "H" pipe, any thoughts on an "H" or "X" pipe, or just straight dual pipes? Not too concerned about burning the tires off with power, just want as good of a sound I can get from a 302 2v.

 

[cazsper]

When it comes to dual exhaust "size"' I have used the following as a guide:

2.00" diameter....... Up to 200hp

2.25" diameter........up to 325hp

2.50" diameter........up to 500hp

3.00" diameter........up to 600hp

I suppose 2.50" dual exhaust would be fine. I would just question if you might want to upgrade at a later date where 2.50" would be necessary. For a street car, very rarely would a smallblock need bigger than 2.50". I like using an X/H pipe. I have read that an X-pipe was better but sounded like a modern car vs an older muscle car. I personally have never heard an H-pipe on a newer (EFI) car and I have never heard an X-pipe on an older (carb) car. However, I do like the sound of an X-pipe with Magnaflow mufflers. So that is what I am planning. Sure you can find come sound clips on YouTube. I hope this helps..

Mike

 

[Danno]

When it comes to dual exhaust "size"' I have used the following as a guide:

2.00" diameter....... Up to 200hp

2.25" diameter........up to 325hp

2.50" diameter........up to 500hp

3.00" diameter........up to 600hp

I suppose 2.50" dual exhaust would be fine. I would just question if you might want to upgrade at a later date where 2.50" would be necessary. For a street car, very rarely would a smallblock need bigger than 2.50". I like using an X/H pipe. I have read that an X-pipe was better but sounded like a modern car vs an older muscle car. I personally have never heard an H-pipe on a newer (EFI) car and I have never heard an X-pipe on an older (carb) car. However, I do like the sound of an X-pipe with Magnaflow mufflers. So that is what I am planning. Sure you can find come sound clips on YouTube. I hope this helps..

Mike

Just looked up and saw a stock 302 2v puts out 220 hp, so I will go with a 2 1/4".

Rookie question, I am assuming that if I get the 2 1/4" "H" or "X" pipe that the flare on the "H" or "X" pipe will seat against the gasket/flange on the stock manifold with no problem, right?

 

[cazsper]

I think it depends on what kit you get. I've used an X-pipe for my '95 GT which just replaced the original X-pipe and I have used just the X for a completely custom exhaust for my '68 coupe tjat I did a 393w swap with a 5-speed TKO. The X-pipes that I have seen, one pipe fits inside the other. Them it is either welded or clamped..


Do you think you may ever upgrade your motor? Not everyone, but most people usually do. I would just hate to build a nice exhaust and have it end up being too small..